Effect of gamma subunit carboxyl methylation on the interaction of G protein alpha subunits with beta gamma subunits of defined composition.
A baculovirus expression system was used to determine the contribution of carboxyl methylation of specific G protein gamma subunits to the interaction between alpha and beta gamma subunits. beta gamma subunits were carboxyl methylated by a membrane bound methyltransferase in Sf9 cells, and periodate-oxidized adenosine inhibited this methylation by 90%. Carboxyl methylation of beta(1) gamma(2), beta(2) gamma(3), and beta(2) gamma(7) enhanced pertussis toxin-catalyzed ADP-ribosylation of alpha(i2) and alpha(i3) by about 2-fold. On the other hand, methylation did not enhance membrane attachment of beta gamma subunits. These results suggest that methylation of isoprenylated gamma subunits is required for optimal G protein-mediated signal transduction, but not membrane attachment.
Rosenberg
S J
SJ
Department of Biochemistry, University of Louisville Health Sciences Center, KY, USA.
Rane
M J
MJ
Dean
W L
WL
Corpier
C L
CL
Hoffman
J L
JL
McLeish
K R
KR
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D002384:Catalysis; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D008745:Methylation; D008780:Methyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D037342:Pertussis Toxin; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D018411:Spodoptera; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D011994:Recombinant Proteins; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D008780:Methyltransferases; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins